To increase the sensitivity of direct Gram-stain examination of body fluid specimens, the specimens are usually:
a. incubated for 18 to 24 hours before stain-ing.
b. centrifuged before staining.
c. examined for at least 1 hour.
d. stained for an additional 5 minutes.
B
To increase the sensitivity of direct Gram-stain examination of body fluid specimens, especially CSF, the specimens are usually centrifuged (2000 rpm for 10 minutes), and the smear is prepared from the resulting pellet. This concentration step can increase the sensitivity of direct microscopic examination by fivefold to tenfold.
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